Matsumoto in U.S. Pat. No. 4,165,560 has disclosed a method for manufacturing a diamond playback stylus for use with a capacitive information disc system. A conical tip is ground into one end of the diamond dielectric support element. An electrode-bearing surface is formed in the tip. A record-engaging surface substantially orthogonal to the electrode-bearing surface is formed in the tip. Two surfaces which converge and are substantially flat are formed such that the intersections of the two flat surfaces with the record-engaging surface define the sides of the record-engaging surface.
Dholakia in a copending application entitled "FLIP-FLOP GRINDING METHOD," Ser. No. 292,284 filed Aug. 12, 1981 incorporated herein by reference, discloses a method for preparing a capacitive information disc playback stylus where two flats of substantially the same dimensions are lapped in a cone-shaped tip of a stylus support element. The method includes the steps of contacting a first region of the tip wherein a flat is to be lapped with an abrasive lapping surface for a predetermined time, rotating the element to a second region wherein a flat is to be lapped while the cone is in contact with the lapping surface without the cone tip disturbing or penetrating the lapping surface, contacting the second region of the cone with the abrasive lapping surface for a predetermined time, and repeating these steps until the two flats have been lapped.
It would be advantageous to have an apparatus suitable for carrying out the flip-flop lapping method of Dholakia.